PROJECT SUMMARY/ABSTRACT The need for an efficient, low-cost, yet comprehensive measure to evaluate and track infant/toddler development and treatment outcomes is vital. Such a measure, coupled with a systematic method to gather this information, does not exist. The NICHD Child Development and Behavior Branch identified this need as a research priority, further noting the importance of a measure that can be linked with developmental changes in the brain. We propose the development and testing of a novel measure that collects consistent data from parents/caregivers to characterize infant/toddler development over time, similar to growth curves for height and weight. Clinicians currently rely on information caregivers share at well-child visits, which can be difficult to synthesize when evaluating a young child?s developmental trajectories. Information gathered via our proposed innovative measure also has potential to become common data elements (i.e., universally accepted and standardized data) to promote infant/toddler health, setting the stage for identifying the earliest risk indicators and trajectories of neurodevelopmental disorders. The overall objective of this application is to further develop and validate PediaTracTM, a web-based measure designed to engage parents/caregivers in the gathering of longitudinal, real-time, multi-domain data on infant/toddler development beginning at birth. Our long-term goal is to develop the PediaTrac measure to become a standard for monitoring development and early detection in the primary clinical care setting. Core domains of early development assessed with PediaTrac include feeding/eating, sleep, sensorimotor, social-communication/cognition, and attachment. Information also is obtained about demographic, medical, and environmental factors. Using this approach that systematically measures these domains during a schedule that corresponds to well-child visits (newborn (NB), 2-, 4-, 6-, 9-, 12-, 15-, 18-months), we will establish trajectories of typical/atypical development across critical domains of functioning for infants and toddlers. We will meet the objective of the application through these aims: Aim 1: Using a longitudinal study of 360 parents/caregivers of term infants, we will assess the aforementioned domains on the well-child visit schedule to refine PediaTrac?s items and scales as well as evaluate PediaTrac?s ability to reveal expected variation in the population across the domains assessed, providing both valid and reliable information about infant and toddler development. Aim 2: Using the aforementioned longitudinal sample plus 240 parents/caregivers of high-risk infants (< 37 weeks gestational age), we will use statistical modeling methods to demonstrate that PediaTrac can identify subgroups and their unique longitudinal trajectories. Aim 3: We will examine the ability of the PediaTrac domains at each sampling period to individually and cumulatively predict overall development at 24 months in a subsample of 100 participants. Our expected outcome is an easy to use, yet powerful measure and method that could substantially improve the public health of infants and toddlers by refining our understanding of aggregate and individualized risks and subsequently inform early intervention.